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Can you solve Seth Godin's math problem?

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Re: Can you solve Seth Godin's math problem?

#2

Post by apotheon »

That would only be a "math problem" if it came with enough numbers to do some calculations.

Oh, wait -- he's probably assuming that the only worthwhile metric in the problem is fuel usage. Well, with that requirement, it's easy. Hell, I've even done the calculations for determining how long it would take to recoup my losses if I bought a motorcycle and used that instead of a car with decent fuel efficiency, given some assumptions about future gas prices, a while ago:

http://sob.apotheon.org/?p=449

Re: Can you solve Seth Godin's math problem?

#3

Post by jws »

If we americans worked in gallons/mile instead these sorts of decisions would be obvious and intuitive. No one goes out with the goal of burning a gallon of gas so measuring how many miles you can go by burning one is silly. mpg is the reciprocal of what they want and people are bad at reciprocals.

I fixed his problem below:

  Suburbans: 23.5 liter/100km
  Priuseses:  4.7 liter/100km

  Suburban+: 18.0 liter/100km (save 5.5 liters)
  PriusPlus:  2.3 liter/100lm (save 2.4 liters)

  Would you rather save, 5.5 liters or 2.4 liters?
(And you don't have to "go metric", just using gallons/1000miles would do fine.)

Re: Can you solve Seth Godin's math problem?

#4

Post by JimmyL »

The root of the problem is that we shouldn't be thinking in miles per gallon - we should be thinking in gallons per mile.

The follow-up problem is that average person think miles per gallon is linear (as they would phrase it, "the difference between 1MPG and 2MPG is the same as the difference between 60MPG and 61MPG") because they don't know any better, whereas it's really an inverse/reciprocal relationship.

I wrote a more though explanation of this - http://www.daniellanger.com/blog/2009/08/miles-per-gallon-vs... - the last time MPG came up in discussion, when there was some minor outrage over the Volt claiming 230MPG.

Re: Can you solve Seth Godin's math problem?

#5

Post by mnemonicsloth »

The premise is flawed. We start with: Let's say your goal is to reduce gasoline consumption.

And then we start talking about fuel efficiency. IIRC, though, it's pretty well established in the economics literature that increasing fuel efficiency doesn't reduce gas consumption much, if at all. Increased fuel efficiency means lower effective gas prices, which people respond to by driving more.

The net effect is about the same level of fuel consumption, with more cars on the road (i.e. more traffic and more accidents).

If you want to reduce gas consumption, you have to increase the price. Good ways of doing this include taxing it, increasing demand for other stuff made from petroleum, or reducing supply.

Re: Can you solve Seth Godin's math problem?

#6

Post by lacker »

JimmyL wrote: post #4

The root of the problem is that we shouldn't be thinking in miles per gallon - we should be thinking in gallons per mile. The follow-up problem is that average person think miles per gallon is linear (as they would phrase it, "the difference between 1MPG and 2MPG is the same as the difference between 60MPG and 61MPG") because they don't know any better, whereas it's really an inverse/reciprocal relationship. I wrote…

we should be thinking in gallons per mile

The average person is pretty bad at dealing with fractions, too. Are they going to get the difference between 0.05 gpm and 0.04 gpm? Seems pretty small, it's just 0.01!

Re: Can you solve Seth Godin's math problem?

#7

Post by JimmyL »

lacker wrote: post #6
JimmyL wrote: post #4

The root of the problem is that we shouldn't be thinking in miles per gallon - we should be thinking in gallons per mile. The follow-up problem is that average person think miles per gallon is linear (as they would phrase it, "the difference between 1MPG and 2MPG is the same as the difference between 60MPG and 61MPG") because they don't know any better, whereas it's really an inverse/reciprocal relationship. I wrote…

we should be thinking in gallons per mile The average person is pretty bad at dealing with fractions, too. Are they going to get the difference between 0.05 gpm and 0.04 gpm? Seems pretty small, it's just 0.01!

Valid - gallons/100mi would probably be a more user-friendly measure.

Another interesting argument, although I can't find a source offhand, was to force manufacturers to display a gallons/10,000mi - on the basis that since the average American drives something like 10Kmi per year, this would convey much more concretely the longer-term difference between fuel consumption.

Re: Can you solve Seth Godin's math problem?

#9

Post by RiderOfGiraffes »

I find the easiest thing to do is assume we drive some distance, then work out how much gas is used.

If we drive 1300 miles the numbers all work out easily (because it's divisible by 10, 50 100 and 13)

Suburbans get 10 mpg: 130 gallons

Priuses get 50 mpg: 26 gallons.

Suburbans @ 13 mpg: 100 gallons (30 gallons improvement)

New Prius @ 100 mpg: 13 gallons (13 gallons improvement)

So clearly the best thing to do is scrap all the Suburbans and replace each with a newer style Prius.

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